Reducing the corrosivity of vanadiumcontaining oils



United.S atesParehto,"

" 2,911,292 Patented Nov. 3, .1959

.7 fuel oils containing vanadium to produce, when burned,

an ash which will corrode boiler tubes and boiler tube supports andcause slagging offire bricks.

Residual fuel oils contain very small amounts of metals such. asvanadium, calcium, iron,-nickel, molybdenum, sodium, etc. Some of theseelements are introduced during the refining of the oils. Others arepresent in the original crude either in fine suspension or in the formof soluble organic compounds. When the oil is burned in industrialinstallations these metals are transformed into oxides which aregenerally partly blown out of the stacks and partly remain as flue dust.When this fiue dust contains vanadium and is deposited on the surface ofthe boiler tubes or the fire brick walls, corrosion and/or slaggingresults. The extent of this corrosion and slagging is a function of themelting point of the dust and its content of free vanadium pentoxideremaining in excess depending on the metal content of the oil. Thisoxide melts at 690 C. and is extremely corrosive, attacking every metal,even platinum and silica when in the molten state. Furthermore, vanadiumpentoxide, due to its relatively low melting point will be projected indroplets which will remain liquid (particularly in small installationswith restricted-size combustion chambers) and will collect additionaldust particles.

It has now been found that the corrosive effect of this vanadiumpentoxide may be eliminated or at least greatly reduced by the additionto the oil, prior to burning, of an oil soluble metal compound whichwill combine with the vanadium pentoxide and form a vanadate ofsuflicient- 1y high melting point that it will not be melted during thecombustion of the oil. The minimum melting point which such a vanadateshould possess is above 1600 F. since the temperature reached in thecombusion of fuel oil does not quite reach that high. The only vanadateswhich have been found to possess fusion points as high as 1600 F. areiron, nickel and aluminum meta vanadates. The nickel and aluminumvanadates are particularly efiicient since both have melting pointsabove 2000" F. However, the use of nickel is preferred since theaddition of aluminum salts may cause gelling of the fuel oil. 7

Among the oil soluble metal compounds which are suitable are the metalderivatives of acids such as naphthenic acids and fatty acids,phenolates, salts of alkylated phenol sulfides such as di-isobutylphenol'sulfide, salicylates, salts of thiophosphorus acid esters such asdilauryl, thiophosphoric acid, chelates such as the metal derivatives ofcompounds having difunctional groups, for example diamine and diketocompounds of the type of pentane-dione.

The metal compounds may be added to the oil at any time prior tocombustion and in approximately the stoichiometric proportions necessaryto form the corresponding meta vanadate. The exact amount depends uponthe metal but may easily be calculated from the .0l% for nickel,calculated as the metal.

amount of vanadium pentoxide present in the oil which is usually from0.0001 to 0.05%. This amounts tofbetween 0.00001 and 0.005% foraluminum, between 0.00002 and 0.01% for iron, and between 0.00002 andThe. actual amount of metal compound added will also depend upon thepresence of naturally occurring nickel or ironisalts in' .the oil. Ifthese are appreciable, the amount'added to combine with the vanadiumwould be correspondingly less. f

Although .the addition agents of the present invention maybe added toanyfuel oil, 'they are-especially adapted for use in conjunctionwith'residual or bunker fuels.

These fuels have gravities in the range from 1r fto 15 1 API andfurol'viscosities at 122 F. in the range from 25 seconds to 300 seconds.From what has been'said, therefore, in a specific embodiment of theinventionzythe nickel derivativeof naphthenic acid may'be employed ina'vanadium-containing residual fuel inan amountisuch that the nickelwillv be present in the fuel in a proportion sufficient to 'form'nickelmeta vanadate -wi t-h;, the vanadium.

. In order to more fully illustrate the present invention, the followingexamples are given:

Example 1 The vanadates of aluminum, nickel, iron and magnesium wereprepared and the melting point of each was obtained with the followingresults:

Compound: Melting point, F. Aluminum vanadate 2100 Ferric vanadatel6l5l630 Nickel vanadate 2000+ Magnesium vanadate 1290-1330 The nickelvanadate was analyzed and found to contain 39.2% vanadium and 25.2%nickel. The vanadium content corresponds very closely to the theoreticalfor nickel meta vanadate (Ni(VO but the nickel content is 10% too high,due probably to occluded salts. Since the vanadium pentoxide content offuel oil varies from 0.0001 to 0.05%, the addition of 0.00002 to 0.01%nickel will be necessary to form the theoretical amount of nickel metavanadate.

Example 2 A sample of a Venezuela fuel oil ash containing 25% vanadiumwas found to have a melting point between 1500 and 1550 F. Sufficientanhydrous sodium sulfate was added to this ash to make the sodiumcontent about 11%. The melting point of this material was found to bebetween 1200 and 1300 F. Sufficient nickel oxide (19.4%) was added tocombine with the vanadium present and the melting point was found tohave increased to between 1850 and 1950 F.

The nature of the present invention having been thus fully set forth andspecific examples of the same given, what is claimed as new and usefuland desired to be secured by Letters Patent is:

1. A fuel composition comprising a major amount of a residual fuel oilyielding a corrosive vanadium containing ash upon combustion, and aminor amount, sufficient to retard the corrosiveness of said ash of anoilsoluble metal compound selected from the group consisting of theoil-soluble compounds of iron, aluminum, and nickel, said fuel oilcomposition in the absence of said metal compound normally yielding acorrosive vanadium containing ash upon combustion.

2. A liquid fuel composition adapted to be burned at substantiallyatmospheric pressure without corroding the equipment comprising aresidual fuel oil containing vanadiu-m and an oil-soluble metal compoundselected from the group consisting of the oil-soluble compounds of iron,

aluminum and nickel, said metal compound being present in the amountrequired to react substantially stoichiometrically with the vanadiumupon combustion of the fuel oil to form a meta vanadate of the metal.

3. Composition as defined inclaim 2 in which the metal compound is anoil-soluble nickel compound.

4. Composition as defined in claim 2 in which the metal compound is anoil-soluble iron compound.

5. Composition as defined in claim 2 in which the metal compound is anoil-soluble aluminum compound.

6. Composition as defined in claim 3 in which the amount of nickelcompound added, calculated as nickel,

is between 0400002 and 0.01% of the residual fuel.

' 7. Composition as defined in claim 4in. which the amount of ironcompound added, calculated as iron, is between 0.00002 and 0.01% of theresidual fuel.

8. Composition as defined in claim 5 in which the amount of aluminumcompound added, calculated as aluminum is between 0.00001 and 0.005% ofthe residual fuel.

9. A liquid fuel oil composition adapted to be burned at substantiallyatmospheric pressure without corroding the equipment comprising aresidual fuel oil containing vanadium to which is added a substantiallystoichiometrie amount of an oil-soluble nickel salt of a high molecularweight fatty acid which-will react with the vanadium pentoxide to form avanadate of the metal melting above 1600 F.

10. A liquid fuel oil composition adapted to be burned at substantiallyatmospheric pressure without corroding the equipment comprising aresidual fuel oil containing vanadium to. which. is added asubstantially stoichiometric amount of an oil-soluble nickelnapththenate which will react with the vanadium pentoxide to form avanadate of the metal melting above 1600 F.

References Cited in the file of this patent v V UNITED STATES PATENTS2,230,642 Fischer et al. Feb. 4, 1941 2,301,795 Proell a Nov. 10, 19422,338,578 Downing Jan. 4, 1944 2,560,542 Bartleson. July 17,1951

FOREIGN PATENTS 445,506 Great Britain .4. Apr. 14, 1936 496,692 GreatBritain Dec. 5, 1938 OTHER REFERENCES Dunstan et al.: The Science ofPetroleum, Oxford Univ. Press, New York, N.Y., 1.93 8-, vol. 2, page1053.

1. A FUEL COMPOSITION COMPRISING A MAJOR AMOUNT A RESIDUAL FUEL OILYIELDING A CORROSIVE VANADIUM CONTAINING ASH UPON COMBUSTION, AND AMINOR AMOUNT, SUFFICIENT TO RETARD THE CORROSIVENESS OF SAID ASH OF ANOILSOLUBLE METAL COMPOUND SELECTED FROM THE GROUP CONSISTING OF THEOIL-SOLUBLE COMPOUNDS OF IRON ALUMINUM, AND NICKEL, SAID FUEL OILCOMPOSITION IN THE ABSENCE OF SAID METAL COMPOUND NORMALLY YIELDING ACORROSIVE VANADIUM CONTAINING AS UPON COMBUSTION.